Ida E. Bailey

Group hunting within the Carnivora: physiological, cognitive and environmental influences on strategy and cooperation

Cooperative hunting is believed to have important implications for the evolution of sociality and advanced cognitive abilities. Variation in the level of hunt organisation amongst species and how their cognitive, behavioural and athletic adaptations may contribute to observed patterns of cooperative hunting behaviour, however, are poorly understood. We, therefore, reviewed the literature for evidence of different levels of hunt organisation and cooperation in carnivorans and examined their social and physical adaptations for hunting. Descriptions of group hunting were scarce for many species and often of insufficient detail for us to be able to classify the level of hunt organisation involved. However, despite this, reports of behaviour fitting the description of collaboration, the most advanced level of hunt organisation, were found in over half the carnivorans reported to hunt cooperatively. There was no evidence that this behaviour would require advanced cognitive abilities. However, there was some evidence that both social mechanisms reducing aggression between group members and information transfer amongst individuals may aid cooperative hunting. In general, the cooperative strategies used seemed to depend partly on the species’ locomotor abilities and habitat. There was some evidence that individuals take on consistent roles during cooperative hunts in some species, but it was not clear if this reflects individuals’ physical differences, social factors or life experiences. Better understanding of the social, cognitive and physical mechanisms underlying cooperative hunting, and indeed establishing to what degree it exists in the first instance, will require more data for multiple individuals and species over many hunts.

Physical cognition: birds learn the structural efficacy of nest material.

It is generally assumed that birds’ choice of structurally suitable materials for nest building is genetically predetermined. Here, we tested that assumption by investigating whether experience affected male zebra finches’ (Taeniopygia guttata) choice of nest material. After a short period of building with relatively flexible string, birds preferred to build with stiffer string while those that had experienced a stiffer string were indifferent to string type. After building a complete nest with either string type, however, all birds increased their preference for stiff string. The stiffer string appeared to be the more effective building material as birds required fewer pieces of stiffer than flexible string to build a roofed nest. For birds that raised chicks successfully, there was no association between the material they used to build their nest and the type they subsequently preferred. Birds’ material preference reflected neither the preference of their father nor of their siblings but juvenile experience of either string type increased their preference for stiffer string. Our results represent two important advances: (i) birds choose nest material based on the structural properties of the material; (ii) nest material preference is not entirely genetically predetermined as both the type and amount of experience influences birds’ choices.

Neural correlates of nesting behavior in zebra finches (Taeniopygia guttata)

Highlights • We compare markers of neural activity to nesting behavior in zebra finches.• We visualized immediate early gene (Fos) expression in nesting and control finches.• Fos production in motor, social, and reward neural circuits correlated with nesting.• Fos production correlated with material pick-up in male nesting finches.• Fos production correlated with time spent in the nest in female nesting finches.

Birds build camouflaged nests

ABSTRACT It is assumed that many birds attempt to conceal their nests by using camouflage. To our knowledge, however, no previous experimental studies have explicitly tested this assumption. To explore whether birds choose materials that match the background colors of nest sites to reduce the conspicuousness of their nests, we offered nest-building male Zebra Finches (Taeniopygia guttata) a choice of nest materials that either matched or did not match the color of their nest cup and the surrounding cage walls. Males chose to nest predominantly with material that matched the background color of the cage. To our knowledge, this is the first experimental evidence that birds actively select materials that camouflage their nests.

Nest-building males trade off material collection costs with territory value

Abstract Building a structurally robust nest is crucial for reproductive success in many birds. However, we know little about the criteria birds use to select material or where they go to collect it. Here we observed the material collection of male Cape Weavers (Ploceus capensis). Males typically selected long, strong material to build their nests and each male collected material from different locations. Males that built more nests nested in a different area of the colony and flew further to collect nest material than did males that built fewer nests. As these males that flew further to collect material had longer tails and wings and attracted more females to their territories than did males that flew shorter distances, they may have traded off the travel costs of collecting nest materials with benefits gained from holding a territory in a more ‘desirable’ part of the colony. Nest construction, then, appears to be a multi-dimensional task whereby birds take into account materials structural properties, material proximity to the nest site and territory quality. Males that do this effectively both attract more mates and provide structurally sound nests for their young.

Food preference and copying behaviour in zebra finches, Taeniopygia guttata

As a social species zebra finches might be expected to copy the food choices of more experienced conspecifics. This prediction has been tested previously by presenting observers with two demonstrator birds that differ in some way (e.g., sex, familiarity), each feeding on a different colour food source. However, if the observer subsequently exhibits a preference, it is unclear whether it has copied the choice of one demonstrator or avoided the choice of the other. Furthermore, this choice may actually be influenced by pre-existing preferences, a potential bias that is rarely tested. Here we examine whether apparent copying or avoidance can be explained by pre-existing preferences. In Experiment 1, observers had the opportunity to watch a conspecific forage from one of the two differently coloured food hoppers. In Experiment 2, the observers did not have this opportunity. In both experiments observers were subsequently tested for their food hopper preference and all but one preferred one colour over the other. In Experiment 1 some observers showed evidence for copying, while others seemed to avoid the colour preferred by the demonstrator. In Experiment 2 females generally preferred the white hopper. Pre-existing colour preferences could, therefore, explain the apparent copying/avoidance we observed. This article is part of a Special Issue entitled: Cognition in the wild.

Microsatellite variation in Rufous Hummingbirds (Selasphorus rufus) and evidence for a weakly structured population

AbstractThe Rufous Hummingbird (Selasphorus rufus) population is declining in some areas of North America, but not in others. The reasons for the decline are, as yet, unknown. Understanding the genetic population structure of this species could be useful in understanding its dispersal behaviour and whether particular geographical areas should be treated as separate conservation units. We tested 16 microsatellite markers designed for other hummingbird species for amplification in Rufous Hummingbirds. Using six polymorphic markers, we found that the Rufous Hummingbird population was weakly structured such that birds breeding in central British Columbia could be distinguished from those breeding on Vancouver Island and those in Alberta, each several hundred kilometres away. Whether landscape features such as the Rocky Mountains and Fraser River Valley significantly affect dispersal patterns requires further investigation.ZusammenfassungGenetische Variabilität und Struktur bei der Rotrücken-Zimtelfe Die Rotrücken-Zimtelfe (Selasphorus rufus), eine Kolibriart in Nordamerika, nimmt in manchen Gebieten ab, in anderen jedoch nicht. Die Ursachen des Bestandsrückgangs sind bisher jedoch weitgehend unbekannt. Um entsprechende Schutzstrategien für die einzelnen Populationen gezielt entwickeln zu können, ist ein besseres Verständnis der genetischen Struktur und damit der Wanderbewegungen zwischen den einzelnen Populationen notwendig. Insgesamt wurden in dieser Arbeit 16 Mikrosatellitenmarker anderer Kolibriarten getestet und auf ihre artspezifische Eignung hin überprüft. Sechs polymorphe Marker konnten erfolgreich für die Analysen bei S. rufus etabliert werden. Die Populationen zeigten nur geringe genetische Unterschiede, Individuen aus Vancover Island, British Columbia, und Alberta ließen sich jedoch unterscheiden. Welche Rolle Bergzüge wie die Rocky Mountains oder Täler wie das Fraser River Valley für das Dispersal der Art hat, sollte in zukünftigen Studien genauer analysiert werden.

Do sunbirds use taste to decide how much to drink

Nectarivorous birds typically consume smaller meals of more concentrated than of less concentrated sugar solutions. It is not clear, however, whether they use taste to decide how much to consume or whether they base this decision on post-ingestive feedback. Taste, a cue to nectar concentration, is available to nectarivores during ingestion whereas post-ingestive information about resource quality becomes available only after a meal. When conditions are variable, we would expect nectarivorous birds to base their decisions on how much to consume on taste, as post-ingestive feedback from previous meals would not be a reliable cue to current resource quality. Here, we tested whether white-bellied sunbirds (Cinnyris talatala), foraging from an array of artificial flowers, use taste to decide how much to consume per meal when nectar concentration is highly variable: they did not. Instead, how much they chose to consume per meal appeared to depend on the energy intake at the previous meal, that is how hungry they were. Our birds did, however, appear to use taste to decide how much to consume per flower visited within a meal. Unexpectedly, some individuals preferred to consume more from flowers with lower concentration rewards and some preferred to do the opposite. We draw attention to the fact that many studies perhaps misleadingly claim that birds use sweet taste to inform their foraging decisions, as they analyse mean data for multiple meals over which post-ingestive feedback will have become available rather than data for individual meals when only sensory information is available. We discuss how conflicting foraging rules could explain why sunbirds do not use sweet taste to inform their meal size decisions.